Process integration method to tune resistivity of nickel silicide

ABSTRACT

Methods for depositing a low resistivity nickel silicide layer used in forming an interconnect and electronic devices formed using the methods are described herein. In one embodiment, a method for depositing a layer includes positioning a substrate on a substrate support in a processing chamber, the processing chamber having a nickel target and a silicon target disposed therein, the substrate facing portions of the nickel target and the silicon target each having an angle of between about 10 degrees and about 50 degrees from the target facing surface of the substrate, flowing a gas into the processing chamber, applying an RF power to the nickel target and concurrently applying a DC power to the silicon target, concurrently sputtering silicon and nickel from the silicon and nickel targets, respectively, and depositing a NixSi1-x layer on the substrate, where x is between about 0.01 and about 0.99.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 62/521,100, filed on Jun. 16, 2017, which is hereinincorporated by reference in its entirety.

BACKGROUND Field

Embodiments described herein generally relate to the field ofsemiconductor device manufacturing, and more particularly, to methods offorming metal silicide interconnects using a co-sputtering physicalvapor deposition (PVD) process in a multi-cathode PVD chamber, andelectronic devices formed using the methods.

Description of the Related Art

As the circuit density for next generation devices increases andtransistor dimensions continue to shrink, the properties of thematerials used for wire interconnects begins to dominate deviceperformance for major performance metrics including power consumption,resistance-capacitance (RC) delay, and reliability. Copper has been usedfor wire interconnects in advanced USLI and VSLI technologies for thepast two decades because copper generally exhibits relatively lowresistivity, and thus high conductivity. However, as the widths of theinterconnect wiring of a device shrink to dimensions at or belowelectron mean free path (eMFP) of the interconnect wiring material, theeffective resistivity of the material is increased as a result ofundesirable side-wall electron scattering at the surface of theinterconnect wiring and the grain boundary interfaces thereof. Thus, theeffective resistivity of copper, typically used in interconnects, beginsto increase for copper interconnects having a width below copper's eMFPof 39 nm and increases dramatically for interconnects having a width of20 nm or below. In addition, the barrier layer used with copperinterconnects to prevent undesirable diffusion of the copper materialinto surrounding dielectric material contributes to an increased overallresistivity of the wire interconnect.

Accordingly, there is a need in the art for alternative conductormaterials.

SUMMARY OF THE DISCLOSURE

Embodiments described herein generally relate to methods ofmanufacturing a semiconductor device and, in particular, relate tomethods of co-sputtering a nickel silicide layer onto a substrate in amulti-cathode physical vapor deposition (PVD) chamber.

In one embodiment, a method for depositing a layer includes positioninga substrate on a substrate support in a processing chamber, theprocessing chamber having a nickel target and a silicon target disposedtherein, the substrate facing portions of the nickel target and thesilicon target each having an angle of between about 10 degrees andabout 50 degrees from the target facing surface of the substrate,flowing a gas into the processing chamber, applying an RF power to thenickel target and concurrently applying a DC power to the silicontarget, concurrently sputtering silicon and nickel from the silicon andnickel targets, respectively, and depositing a Ni_(x)Si_(1-x) layer onthe substrate, where x is between about 0.01 and about 0.99.

In another embodiment, a method of forming a device includes positioninga substrate on a substrate support within a processing chamber, thesubstrate having a plurality of features disposed thereon and aplurality of openings disposed between the plurality of features,flowing a gas into the processing chamber, applying an RF power to anickel target and concurrently applying a DC power to a silicon target,wherein the nickel target and the silicon target are disposed in theprocessing chamber and the surfaces thereof facing the substrate eachhave an angle to the surface of the substrate facing the targets ofbetween about 10 degrees and about 50 degrees, concurrently sputteringsilicon and nickel from the silicon and nickel targets, respectively,and depositing a Ni_(x)Si_(1-x) layer, where x is between about 0.01 andabout 0.99, on the substrate to form a plurality of interconnects.

In another embodiment, an electronic device features a patternedsubstrate comprising a dielectric layer and a plurality of interconnectfeatures disposed in the dielectric layer, wherein the plurality ofinterconnect features comprise Ni_(x)Si_(1-x) having an effectiveresistivity about 30 μohm-cm or less, x is between about 0.4 and about0.6, and one or more of the interconnect features has a width of lessthan about 20 nm and a height about 2 times the width or more.

In another embodiment, a method of depositing a layer comprising nickeland silicon includes positioning a substrate on a substrate support in aprocessing chamber, the processing chamber having a nickel target and asilicon target, the nickel target and the silicon target having an angleto a surface of the substrate support of between about 10 degrees andabout 50 degrees, flowing an inert gas into the processing chamber,applying an RF power to the nickel target and a DC power to the silicontarget, where a ratio of the RF power and the DC power is between about1:1 and about 1:12, and co-sputtering a Ni_(x)Si_(1-x) layer onto thesubstrate, the Ni_(x)Si_(1-x) layer having a resistivity of less thanabout 200 μohm-cm, where x is between about 0.01 and 0.99.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 shows the relationship between scaling of wire interconnects to50 nm and below and material selection for those wire interconnects.

FIG. 2A is a cross-sectional view of a multi-cathode processing chamberused to practice the embodiments disclosed herein.

FIG. 2B shows the relative positions of a target and a substrate duringdeposition in the processing chamber of FIG. 2A.

FIG. 2C is a schematic view showing a shield assembly disposed in thechamber lid of a processing chamber used to practice the methodsdisclosed herein.

FIG. 3A shows the resistivity of nickel silicide layers depositedaccording to the embodiments disclosed herein.

FIG. 3B compares the resistivity of layers copper, annealed cobalt,annealed ruthenium, and nickel silicide, where the nickel silicidelayers are deposited according to the methods described herein.

FIG. 4 is a flow diagram setting forth a method of depositing a nickelsilicide layer onto a substrate, according to embodiments disclosedherein.

FIGS. 5A-5C illustrate the formation of wire interconnects, using themethod set forth FIG. 4.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally describe a method fordepositing a layer of nickel silicide onto a substrate, including overpreviously formed layers on the substrate, using a co-sputteringphysical vapor deposition (PVD) process in a multi-cathode PVD chamber,and in particular, controlling the resulting resistivity, composition,and crystal orientation of the deposited nickel silicide layer bycontrolling the power and the ratio of power applied to the nickel andsilicon targets.

FIG. 1 shows the relationship between scaling of a trench to a thicknessof 50 nm and below and material selection for wire interconnects, wherescaling refers to the changes in line resistivity (wire resistivity) ofselected materials as wires narrow to and beyond the electron mean freepath eMFP of the material. In FIG. 1 the interconnect wires are intrenches disposed in a dielectric material and have widths of 50 nm andbelow (trench CD) with an aspect ratio (depth to width) of 2:1. FIG. 1shows the relationship between the effective resistance of copper 105,cobalt 103, and nickel silicide 101, wherein a liner/barrier layer isinterposed between the copper, cobalt or nickel silicide and thedielectric material to prevent diffusion of copper, cobalt or nickelsilicide atoms into the surrounding dielectric material.

As used herein, effective resistivity refers to the measured resistivityof a material, and not the bulk resistivity of the material. As can beseen from FIG. 1, the effective resistivity of the three materialsbegins to meaningfully increase as the widths of the wire interconnectsare scaled to 20 nm and below, but the increase of resistivity of thecobalt 103 (having an eMFP of 9.5) with decreasing trench CD isincrementally less than that of copper 105, making cobalt 103 apromising material for trench CD's of 10 nm and below. In fact, theeffective resistance of copper, which is less than that of cobalt forfeatures in the 10 to 50 nm width range, becomes greater than that ofcobalt at feature sizes slightly smaller than 10 nm wide. Theincremental increase in the effective resistivity of nickel silicide 101(having an eMFP of less than 10 nm depending on the nickel to siliconcomposition) is less than that of the cobalt 103 making nickel silicide101 a promising material for wire interconnects having a trench CD of 7to 8 nm and below, and the effective resistance of cobalt becomesgreater than that of nickel silicide at a line width of around 6 nm.

FIG. 2A is a cross-sectional view of a multi-cathode physical vapordeposition (PVD) processing chamber 200 used for the deposition ofnickel silicide onto a substrate 228, according to the methods describedherein. FIG. 2C is a schematic view showing a cathode shieldconfiguration disposed in the chamber lid 240 of the processing chamber200. The cathode shield configuration shown in FIG. 2C is not shown FIG.2A, however, the methods described herein include the use of a cathodeshield configuration, such as that shown in FIG. 2C, with the processingchamber 200. In this embodiment, the processing chamber 200 isconfigured to process single substrate, such as the substrate 228disposed on a substrate support 226 in FIG. 2A. In other embodiments,the methods described herein are used in a processing chamber configuredto process multiple substrates disposed on a substrate turntable.

Herein, the processing chamber 200 features one or more sidewalls 230, achamber lid 240, and a chamber bottom 234 which define a processingvolume 299. The processing volume 299 is fluidly coupled to a vacuum 209such as one or more dedicated vacuum pumps, and has a substrate support226 disposed therein. The substrate support 226 includes a shaft 224,surrounded by a substrate support bellows 222 outside of the processingchamber, sealingly extending through the chamber bottom 234, the shaft224 raises and lowers the substrate support 226 to facilitate transferof the substrate 228 to and from the processing chamber 200. Thesubstrate 228 is loaded into the processing volume 299 through asealable opening 232 in one of the one or more sidewalls 230, which isconventionally sealed with a door or a valve (not shown) during thedeposition processes. In some embodiments, the shaft 224 is furthercoupled to an actuator 220 which rotates the shaft 224, and thereby thesubstrate 228 disposed on the substrate support 226, during processingwhich, under some process conditions, improves the uniformity of thethickness of the deposited films on the surface of the substrate 228.

The processing chamber 200 includes a plurality of cathodes 250A-E,herein plurality of cathodes comprises five cathodes (250D-E are shownin FIG. 2C), disposed through openings in the chamber lid 240 where eachof the plurality of cathodes 250A-E is configured to sputter one or morematerials onto the substrate 228. In this embodiment, a first cathode250A is configured to sputter nickel from a nickel target 252 and asecond cathode 250B is configured to concurrently sputter (co-sputter)silicon from a silicon target 262 thereby depositing a homogenous nickelsilicide layer on the surface of the substrate 228. Herein, a thirdcathode 250C is configured to sputter titanium from a titanium target264 in the presence of a reactive gas containing nitrogen, such asnitrogen or ammonia, thereby depositing a titanium nitride layer on thesurface of the substrate 228. In other embodiments, the third cathode250C is configured to sputter titanium nitride from a titanium nitridetarget.

One or more of the plurality of cathodes 250A-E includes a magnetassembly 254 disposed within a housing volume 267 defined by the cathodehousing 255 and a target backing plate 253, the target backing plate 253having a target, such as the nickel target 252 disposed thereon. Themagnet assembly 254 is coupled to a rotating shaft 256 which is coupledto a motor 258 that rotates the rotating shaft 256, and thus the magnetassembly 254 over the rear-non sputtered, side of the target backingplate 253. Each of the plurality of cathodes 250A-E are coupled to apower supply, such as the RF power supply 263 coupled to the firstcathode 250A and to the third cathode 250C or the DC power supply 265coupled to the second cathode 250B. In other embodiments, the DC powersupply 265 is a pulsed DC power supply. Sputtering and/or reactive gasesare provided to the processing chamber through a gas inlet 211.

Each of the plurality of cathodes 250A-E include a bellows 257 and anangular adjustment mechanism (not shown) coupled to the exterior of thechamber lid 240 and to the cathode housing 255. The bellows 257 is usedto maintain the vacuum condition of the processing volume 299 bypreventing the passage of atmospheric gases into the processing volume299, and leakage of processing gases from the processing volume 299 tothe surrounding environment. The angular adjustment mechanism is used toalter, and then fix, the position the cathode housing 255 and thus atarget disposed therein, such as the nickel target 252 of the firstcathode 250A, at an angle relative to the surface of the substrate 228described in further detail with reference to FIG. 2B.

FIG. 2B shows the relative position of a target 260, such as any of thetargets of the plurality of cathodes 250A-E in the processing chamber200, to a substrate 228 during deposition. Herein, the substrate 228 hasa diameter of 300 mm and the target 260 has a diameter of less than thediameter of the substrate 228, such as less than about 300 mm, such asbetween about 100 mm and about 300 mm. During processing, the substrate228 is moved to a processing position by raising the substrate support226, shown in FIG. 2A, to where a horizontal plane of the surface of thesubstrate 228 is spaced from the target 260 by a vertical distance Z1.The vertical distance Z1 is measured from the location of the targetthat is closest to the horizontal plane of the surface of the substrate228. Herein, Z1 is between about 100 mm and about 400 mm, such betweenabout 150 mm and about 350 mm, such as between about 200 mm and about300 mm, such as between about 225 mm and about 275 mm. The plane of thesurface of the target 260 is angled with respect to the horizontal planeof the surface of the substrate 228 at an angle θ, where theta isbetween about 10 degrees and about 50 degrees, such as between about 20degrees and about 40 degrees, between about 20 degrees and about 30degrees, or between about 30 degrees and about 40 degrees.

FIG. 2C is a schematic view showing a shield assembly 282 disposed inthe chamber lid 240 of the processing chamber 200. The shield assembly282 includes a plurality of vertical walls 285 extending between each ofthe plurality of cathodes 250A-E where the plurality of vertical walls285 are coupled at center line and extend radially outward therefrom.The plurality of vertical walls 285 are positioned to prevent cross-talkand/or cross-target contamination between two or more of the pluralityof cathodes 250A-E during processing by providing a physical barriertherebetween. Cross-talk refers to an undesirable electricalinterference from one cathode's power supply, such as RF power supply263, with another cathodes power supply, such as DC power supply 265, ina co-sputtering process. Cross-target contamination refers to theundesirable deposition of material from one target onto another targetin a co-sputtering and/or sequential sputtering process.

In some embodiments, the processing chamber 200 further includes one ormore cylindrical shields 280 coupled to one or more of the plurality ofcathodes 250A-E as shown in FIG. 2C. In those embodiments, the one ormore cylindrical shields 280 surround the cathode housings 255 and thusthe targets disposed therein of one or more of the plurality of cathodes250A-C. The cylindrical shields 280 are configured to prevent cross-talkand cross-target contamination by providing a physical barrier betweenthe cathodes in the chamber. In other embodiments, the processingchamber 200 includes the cylindrical shields 280 and does not includethe shield assembly 282.

FIG. 3A shows the resistivity of nickel silicide layers depositedaccording to embodiments disclosed herein. Lines 316, 317, 318, 319 eachrepresent the ratio of the power supplied to the nickel cathode and thepower supplied to the silicon cathode during a co-sputtering PVDprocess, where the power supplied to the nickel cathode, such as thefirst cathode 250A, compared to the power supplied to the siliconcathode, such as the second cathode 250B, increases from a first powerratio represented by line 316 to a fourth power ratio represented byline 319 thereby increasing the ratio of nickel to silicon in thedeposited layers, such that nickel silicide layers deposited at thefirst power ratio 316 are silicon rich layers and the nickel silicidelayers deposited at the fourth power ratio 319 are nickel rich layers.The resistivity of the resulting nickel silicide layers R1-R8, depositedusing the power ratios of lines 316-319 are shown in Table 1. R1 and R5were each deposited using the first power ratio 316, R2 and R6 were eachdeposited using the second power ratio 317, R3 and R7 were eachdeposited using the third power ratio 318, and R4 and R8 were eachdeposited using the fourth power ratio 319.

As shown in FIG. 3, R1-R4 were all deposited at the same DC power whilethe RF power to the nickel target was varied and R4-8 were all depositedat the same RF power while the DC power to the silicon target wasvaried. The effective resistivity of the material layer of ratios R1 toR8 were calculated by measuring the sheet resistance of the depositedfilm, measuring the thickness of the deposited film, and extrapolatingthe effective resistivity of the film from the sheet resistance and filmthickness measurements. Unexpectedly, the resistivity of the depositedlayers did not vary linearly with increasing nickel concentration, forexample while a nickel silicide composition at ratio R2 shows asignificant decrease in effective resistivity as compared to a nickelsilicide composition at ratio R1 which would be expected as the nickelsilicide composition at ratio R2 has a higher concentration of the moreconductive nickel, the nickel silicide compositions at ratios R3 and R4have higher concentrations of nickel than those one at ratio R2, butalso have an increased effective resistivity from the nickel silicidecomposition at ratio R2. Also unexpected, is the difference inresistivity in nickel silicide layers deposited using the same powerratio, such as the first power ratio 316, but at different RF and DCpower levels, where the concentrations of nickel and silicon in the anickel silicide compositions at ratios R1 and R4 are substantially thesame.

While not being bound to any particular theory, it is believed that, inaddition to nickel and silicon concentrations, the crystal orientationof nickel silicide layers, deposited according to methods describedherein, can be controlled by tuning the power levels, and thus thecorresponding power ratios, applied to the nickel and silicon cathodesto deposit the nickel silicide layers with a desired crystal orientationand/or a desired effective resistivity. Further, the methods describedherein can be used to deposit a nickel silicide layer having the desiredcrystal orientation without the need for an anneal process thereafter,or at least without the need for a high temperature anneal process s.This is beneficial at interconnect levels where high temperatures areundesirable due to the low thermal budget of low K dielectric materials.

TABLE 1 Nickel to Nickel to silicide silicide power Resistivity powerResistivity ratio (μohm-cm) ratio (μOhm-cm) First Power R1 38 R5 63Ratio (line 316) Second Power R2 17 R6 43 Ratio (line 317) Third PowerR3 47 R7 47 Ratio (line 318) Fourth Power R4 46 R8 65 Ratio (line 319)

FIG. 3B compares the effective resistivity of layers of differentmaterials, such as copper 321, annealed cobalt 323, annealed ruthenium324, and nickel silicide 325 where the nickel silicide 325 is depositedaccording to the methods described herein. The effective resistivity wasmeasured for layer thicknesses of 25 nm and below. As shown in FIG. 3b ,nickel silicide 325 layers deposited according to methods describedherein, continue to have comparably low effective resistivity ascompared to other interconnect materials at blanket film thicknesses ofless than about 10 nm making nickel silicide a suitable material forsub-10 nm interconnect widths.

FIG. 4 is a flow diagram setting forth a method of depositing a nickelsilicide layer onto a substrate, or onto features disposed on asubstrate. FIGS. 5A-5C illustrate the formation of wire interconnects,using the method 400 set forth in FIG. 4. At activity 410 the method 400includes positioning a substrate, such as a patterned substrate, on asubstrate support in a multi-cathode processing chamber. A patternedsubstrate is illustrated in FIG. 5A where the pattern comprises aplurality of features 535 having a height H and a plurality of openings537 having a width W disposed therebetween. Herein, the plurality offeatures 535 are formed of a dielectric material, such as siliconoxides, SiN, SiOC, SIC, or low-k polymers, such as a polyamide, orcombinations thereof. The width of the openings is less than about 20nm, such as less than about 15 nm, less than about 10 nm, less thanabout 8 nm, less than about 7 nm, such as less than about 5 nm. Theheight H of the plurality of features is equal to or more than about twotimes the width W of the plurality of openings 537. The processingchamber is maintained at a pressure of less than about 1 mTorr, such asbetween 0.5 mTorr and 1 mTorr. In some embodiments, the patternedsubstrate further includes a barrier layer (not shown), such as Ta, TaN,It, W, WN, or combinations thereof. In those embodiments, the barrierlayer is disposed over the plurality of features 535 and serves as aliner in the plurality of openings 537 disposed between the plurality offeatures 535. In some embodiments, the barrier layer is deposited in thesame processing chamber as is a subsequently deposited nickel silicidelayer, and thus without the substrate breaking vacuum between depositionof the barrier layer and deposition of the nickel silicide layer.

At activity 410 the method 400 includes flowing a sputtering gas intothe processing chamber, where the sputtering gas is an inert gas such asargon, helium, or nitrogen.

At activity 415 the method 400 includes applying an RF power to a nickeltarget and forming a first sputtering plasma adjacent to the facethereof. The surface of the nickel target is disposed in the processingchamber at an angle to the surface of the substrate support, and this tothe surface of the substrate disposed thereon, of between about 10degrees and about 50 degrees. The RF power is between about 100 wattsand about 1000 watts. Herein, the RF power is coupled to a backing platehaving the nickel target disposed thereon. In another embodiment, the RFpower is coupled to the nickel target.

At activity 420 the method 400 includes applying DC power to a silicontarget and forming a second sputtering plasma adjacent to the facethereof. The silicon target is disposed in the processing chamber at anangle to the surface of the substrate support, and the surface of thesubstrate disposed thereon, of between about 10 degrees and about 50degrees. The DC power is between about 600 watts and about 1200 wattsand is applied to the silicon target concurrently with applying the RFpower to the nickel target. Herein, the DC power is coupled to a backingplate having the silicon target disposed thereon. In another embodiment,the DC power is coupled to the silicon target. The silicon targetcomprises amorphous silicon, polycrystalline silicon, crystallinesilicon, or combinations thereof. Herein, the ratio of the RF power andthe DC power is between about 1:1 and about 1:12.

At activity 425 the method 400 includes depositing a homogenous nickelsilicide layer 539 (Ni_(x)Si_(1-x), where x is between 0.01 and 0.99,such as between 0.1 and 0.9) by co-sputtering material from the nickeland silicon targets onto the substrate and/or the features disposedthereon. FIG. 58 illustrates depositing the nickel silicide layer 539onto the plurality of features 535 disposed on the substrate 228. FIG.5C illustrates a plurality of interconnects 541 formed according to themethods described above where portions of the nickel silicide layer 539were removed from the surface of the plurality of features 535 using asuitable process, such as an etch or a chemical mechanical polishingprocess, to form an electronic device.

The method 400 hereof is useful to tune the resistivity and compositionof nickel silicide layers by adjusting the RF power, the DC power, andthe ratio therebetween, by adjusting the nickel and silicon targetangles, and by adjusting the pressure of the processing chamber. Forexample, in one embodiment the method 400 is used to deposit a lowresistivity Ni_(x)Si_(1-x) layer, where x is between about 0.4 and about0.6, for example where x is about 0.5. The low resistivityNi_(x)Si_(1-x) layer has a resistivity less than about 30 μohm-cm, suchas between about 10 μohm-cm and about 30 μohm-cm, at a thickness of lessthan about 20 nm, and a full crystalline orientation. The lowresistivity Ni_(x)Si_(1-x) layer is deposited in a processing chamberhaving a pressure of between about 0.6 mTorr and about 0.7 mTorr byco-sputtering nickel and silicon. The faces of the nickel and silicontargets each have an angle of between about 20 degrees and about 40degrees with respect to the surface of the substrate support, and thusfrom the surface of the substrate disposed thereon. In this embodiment,the ratio of RF power and DC power is between about 1:1.6 and about 1:4where the RF power is between about 300 watts and about 500 watts andthe DC power is between about 800 watts and about 1200 watts.

In another embodiment, the method 400 is used to deposit a mediumresistivity Ni_(x)Si_(1-x) layer, where x is more than about 0.6. Themedium resistivity layer has a resistivity of between about 30 μohm-cmand about 60 μohm-cm, such as between about 30 μohm-cm and about 50μohm-cm, at a thickness of less than about 20 nm. The medium resistivityNi_(x)Si_(1-x) layer is deposited in a processing chamber having apressure of between about 0.5 mTorr and about 0.8 mTorr by co-sputteringnickel and silicon where the nickel and silicon targets each have anangle of between about 20 degrees and about 30 degrees from the surfaceof the substrate support, and from the surface of the substrate disposedthereon. In this embodiment, the ratio of RF power to DC power is morethan about 1:2.4, such as more than about 1:1.6, where more than refersto increasing RF power compared to DC power. The RF power is more thanabout 500 watts, for example between about 500 watts and about 1000watts, and the DC power is between about 800 watts and about 1200 watts.

In another embodiment, the method 400 is used to deposit a highresistivity Ni_(x)Si_(1-x) layer, where x is less than about 0.4, suchas less than about 0.33. The high resistivity Ni_(x)Si_(1-x) layer has aresistivity of more than about 60 μohm-cm, such as between about 60μohm-cm and 200 μohm-cm at a thickness less than about 20 nm. The highresistivity Ni_(x)Si_(1-x) layer is deposited in a processing chamberhaving a pressure of between about 0.5 mTorr and about 1 mTorr byco-sputtering nickel and silicon. The nickel and silicon targets eachhave an angle of between about 30 degrees and about 40 degrees from thesurface of the substrate support, and from the surface of the substratedisposed thereon. In this embodiment, the ratio of RF power to DC poweris between about 1:12 and about 1:2. The RF power is between about 100watts and about 300 watts and the DC power is between about 600 wattsand about 1200 watts.

In another embodiment, the method 400 further comprises depositing a TiNpassivation layer on the nickel silicide layer, where the TiNpassivation layer is deposited in the same processing chamber as thenickel silicide layer, and thus without the substrate breaking vacuum.The TiN layer is deposited by flowing a sputtering gas comprising argonand a gas reactive with titanium, such as nitrogen, NH₄, or combinationsthereof, into the processing chamber, applying an RF power to a titaniumtarget, forming a sputtering plasma of the sputtering gas, anddepositing a TiN passivation layer onto the nickel silicide layer. Inanother embodiment, the target comprises TiN and the sputtering gascomprises argon, helium, nitrogen, or combinations thereof.

In some embodiments, the silicon nitride layers are annealed at atemperature of below about 400° C.

The methods described above allow for the deposition of nickel silicidelayers having tunable composition (nickel and silicon concentrations),crystal orientation, and resistivity by adjusting the processingparameters of the multi-cathode processing chamber. With tunableresistivity, nickel silicide layers deposited according to embodimentsdisclosed herein can be used for applications requiring medium or highresistivity, such as devices requiring an embedded resistor, such as aplate resistor, or a line resistor. Further, the low resistivity nickelsilicide layers formed according the embodiments described herein aresuitable for use as interconnects in the sub 20 nm regime as the eMFP'sof nickel silicides, and thus their effective resistivity, allow forscaling of line widths and other conductor feature widths to dimensionsless than what is currently available from other known materials.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A method for depositing a layer, the methodcomprising: positioning a substrate on a substrate support in aprocessing chamber, the processing chamber having a nickel target and asilicon target disposed therein, wherein respective planes of substratefacing portions of the nickel target and the silicon target each form anangle of between about 10 degrees and about 50 degrees with a plane of atarget facing surface of the substrate; flowing a sputtering gas intothe processing chamber; applying an RF power to the nickel target andconcurrently applying a DC power to the silicon target; concurrentlysputtering silicon and nickel from the silicon and nickel targets,respectively; and depositing a Ni_(x)Si_(1-x) layer on the substrate,where x is between about 0.01 and about 0.99.
 2. The method of claim 1,wherein the Ni_(x)Si_(1-x) layer has an effective resistivity less thanabout 30 μohm-cm.
 3. The method of claim 2, wherein x is between about0.4 and 0.6.
 4. The method of claim 3, wherein the DC power is betweenabout 800 watts and about 1200 watts.
 5. The method of claim 4, whereinthe RF power is between about 300 watts and about 500 watts.
 6. Themethod of claim 1, wherein the Ni_(x)Si_(1-x) layer has a resistivity ofbetween about 30 μohm-cm and about 60 μohm-cm.
 7. The method of claim 6,wherein x is more than about 0.6.
 8. The method of claim 7, wherein theRF power is above about 500 watts.
 9. The method of claim 1, wherein theNi_(x)Si_(1-x) layer has a resistivity of between about 60 μohm-cm andabout 200 μohm-cm.
 10. The method of claim 9, wherein x is less thanabout 0.4.
 11. The method of claim 10, wherein the RF power is betweenabout 100 watts and about 300 watts and the DC power is between about600 watts and about 1200 watts.
 12. The method of claim 1, wherein thesputtering gas comprises argon, nitrogen, helium, or combinationsthereof.
 13. The method of claim 12, wherein a pressure in theprocessing chamber is less than about 1 mTorr.
 14. A method of forming adevice, comprising: positioning a substrate on a substrate supportwithin a processing chamber, the substrate having a plurality ofopenings formed in a surface thereof; flowing a gas into the processingchamber; applying an RF power to a nickel target and concurrentlyapplying a DC power to a silicon target, wherein the nickel target andthe silicon target are disposed in the processing chamber and respectiveplanes of substrate facing surfaces thereof each form an angle with aplane of a target facing surface of the substrate of between about 10degrees and about 50 degrees; concurrently sputtering silicon and nickelfrom the silicon and nickel targets, respectively; and depositing aNi_(x)Si_(1-x) layer, where x is between about 0.01 and about 0.99, onthe substrate to form a plurality of interconnects.
 15. The method ofclaim 14, wherein the plurality of interconnects have a width of lessthan about 20 nm.
 16. The method of claim 15, wherein a ratio of the RFpower to the DC power is between about 1:1 and about 1:12.
 17. Themethod of claim 16, wherein the plurality of interconnects have a depthof more than about two times the width.
 18. The method of claim 17,wherein the plurality of interconnects have a resistivity of less thanabout 200 μohm-cm.
 19. The method of claim 18, further comprisingdepositing a titanium nitride layer on the Ni_(x)Si_(1-x) layer, whereindepositing the titanium nitride layer comprises applying an RF power toa titanium target disposed in the processing chamber.
 20. A method offorming a multi-layer stack on a substrate, comprising: positioning asubstrate on a substrate support in a processing chamber, the processingchamber having a titanium target, a nickel target, and a silicon targetdisposed therein, wherein respective planes of the substrate facingportions of the titanium target, the nickel target, and the silicontarget each form an angle of between about 10 degrees and about 50degrees with a plane of a target facing surface of the substrate;depositing a homogenous Ni_(x)Si_(1-x) layer on the substrate, where xis between about 0.01 and about 0.99, comprising: flowing a firstsputtering gas into the processing chamber; and concurrently applying anRF power to the nickel target and a DC power to the silicon target; anddepositing a titanium nitride layer on the Ni_(x)Si_(1-x) layer,comprising: flowing a second sputtering gas comprising nitrogen into theprocessing chamber; and applying an RF power to the titanium target.